Application of IMM filtering to passive ranging

This paper presents an interacting multiple model (IMM) filtering scheme for use in passive ranging with angle-only measurement data (such as with IR sensor data). The application is to an air-to-air multiple target tracking environment. The IMM implementation uses the Modified Spherical Coordinates (MSC) method for one of the filter models and a general acceleration model for the other filter. This method, in effect, provides maneuver detection so that range and range rate estimation errors from the MSC filter are minimized and an accurate covariance matrix is maintained to reflect these errors. The new development is the inclusion of the MSC filter in an IMM filtering system. This implementation differs from standard IMM applications because the filters use very different states and because of the requirement to perform passive range (and range rate) estimation. Thus, a new approach to IMM mixing is developed. The method is illustrated through the use of Monte Carlo simulation results.